RJ45 plugs are popular in the telecommunications industry. RJ45 plugs are used to connect PC computers, telephones, servers, credit card registers and a host of other devices. RJ45 is a type of 8P8C modular connector that was defined by TIA/EIA-568 from the Telecommunications Industry Association and the Electronic Industries Alliance.
RJ45 plugs comprise 8 physical pins. An RJ45 plug and an RJ45 receptacle can connect and provide connectivity from a device to a network, or between devices, or another setup. The devices/networks connected must be able to read and understand communication sent over a cable connecting them. The translation of communication can be governed by the pin/pair assignments given by T568A and T568B from TIA/EIA-568. Other devices may use a different standard. The cables used with RJ45 are typically eight conductor 100-ohm balanced twisted-pair cabling, including, for example, Category 5 cable. Previously, Cat 3 cable was popular, but nowadays Cat 5 or Cat 6 cable is used in many applications.
One disadvantage of RJ45 plugs is the 8 pin limit. This numerical limit places a cap on how fast data can be sent and translated through an RJ45 system.